<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		*{
			margin: 0;
			padding: 0;
		}
		.box{
			width: 200px;
			height: 200px;
			background-color: red;
			position: relative;
/*			相对定位 以自己作为参考点*/
/*			left: ;*/
/*			right: ;*/
/*			top: ;*/
/*			bottom: ;*/
			position: absolute;
			left: 0;
		}
	</style>
</head>
<body>
	<div class="one">
		<div class="box"></div>
	</div>
</body>
</html>